I think there has to be massive benefit to the Rails community before there can be a consideration of adding such a feature.

I could be wrong here, but I'm not sure it will solve some of the more drastic issues of what happens in a production Rails app which I believe to be mostly around memory and garbage collection (from my limited experience and understanding).

You might be able to eke out more performance in terms of having more clients be able to hit a page, but I suspect that might make memory more of an issue, not less.